Gt55 Or Gt60?

[TwinTurboM3]

this is not a RB26. it is a BMW inline six 3.9L

Cannot decide between Gt55 and Gt60.

I know there are many big-boys here and your comments are appreciated.

Use of this car is Highway rolls & drag racing as well.

With the 3.9L displacement which turbo would you use?

Compression ratio. 9,0 to 10.5:1 (C16 all time use, as this is not a daily cruiser. I have a E46 M3 with twin GT3076s for daily use)

Arrow Precision Forged Titanium rods or Forged rods? How will Tit rods behave?

Pistons: which brand would you opt? CP/ Arias?

Main billet caps will be custom produced. There is no billet main cap for this engine.

Cylinder head: I am leaning towards Headgames. Any other reputable head builder?

Cams: Custom cams will be grind as per HKS 280 cam specs used on 2JZE. This is tough, need custom grinding.

Exhaust manifold: not as perfect as a Full-Race. But I will do my best in fabrication, smooth curves, trying to keep the runners close to equal.

Maximum engine speed will be 8800-9000 rpm

Which turbocharger would you choose? GT55 or GT60?

I personally dynoed a Supra with GT45-80 on my own Dyno Dynamics and saw full boost at around 5000 rpm on 3.0L. head was perfectly prepared with agressive Port & Polish and + 2 mm valves.

I have talked to another supra owner, and his full spool is around 6k rpm. With 500 cc extra engine capacity, a GT 55 would spool at around 5300-5500 rpm (assuming the compression ratio is 10,0 and cylinder head is very well prepared)

GT55 power band will be from 5500 to 8800 rpm. Acceptable and will put a smile on the face.

On the other side, GT60 is an unknown application. Cannot get first-hand information about GT60. I only saw this video

At which rpm will the Gt60 spool on this application with 3.9L engine? I fear of having full spool at around 6600-7000 rpm on the 3.9L with the GT60.

Which turbocharger would you choose for this application?

MD __________________

[zebra]

It Wouldnt Be School Holidays Would It?

And What Beemer Has a 3.9 In it?

M3's are 3.2

[TwinTurboM3]

It Wouldnt Be School Holidays Would It?

And What Beemer Has a 3.9 In it?

M3's are 3.2

M3 has 3200 cc

M88 engine has 3.5 to 3.8L capacity. add to that a stroker kit, we end up 3.9L

Apart from the 3.9L project, below is my Twin Gt3076 E46 M3. photo is low resolution...

[rb26s13]

sure doesnt look twin to me.

[TwinTurboM3]

sure doesnt look twin to me.

what you see over is the TOP Mount GT30

now the LOW MOUNT GT3076 is

[TwinTurboM3]

down pipe of LOW MOUNT GT30

[TwinTurboM3]

this is when the TOP MOUNT GT30 was under construction

[TwinTurboM3]

intake manifold during constructionn

[rb26s13]

very nice work and i stand corrected

Edited December 27, 2007 by rb26s13

[TwinTurboM3]

very nice work and i stand corrected

thank you very much. RB family has been helpful and also was a source of inspiration.

i will test different A/R s on the exhaust side, different cams and try to find the best combo on my Dynamics. BTW you Aussie people have a wonderful Dyno, and i am also a lucky owner of dynamics dyno as well.

[zebra]

Nice.

The Reason I Sounded Dubious At first is there are a lot of school students who claim to own all these rediculous cars.

I see the car is LHD so your in the US im Guessing.

Pistons I Personally would go Cosworth Custom Same with Con-Rods as by the looks of it There is no budget on this thing you are building.

Make sure you line bore the Billet mains with them torqued into place because of the difference in materials used (cast iron block - Steel Mains)

As For the Turbo I cant comment Because GT55 and GT60 Mean Nothing with out details like Trim, Comp and Exh A/R Etc Etc.

[Lithium]

Hi Mr twin turbo M3, if the twin GT30R is really yours the I am pretty sure we've communicated albeit under slightly different names.

As For the Turbo I cant comment Because GT55 and GT60 Mean Nothing with out details like Trim, Comp and Exh A/R Etc Etc.

There is only one trim comp/turbine setting for the GT55 and GT60 turbos out there - they have an awesomely wide map and aren't likely to build boost quick enough to surge on a 3.9litre anyway. It'd make sense to go one of the smallest turbine a/rs on a BMW.

You mention rev range etc - what boost level/power level are you actually after? GT5591 is a HUGE turbo, I'd not even consider a GT60 and barely think about a GT55. The GT60 you showed, and the only other GT60 I've seen used were both on 26Bs which would provide a shiteload more exhaust gas than a 3.9l BMW though I guess you have to consider compressor efficiency, spinning a 3.9 to near 9000rpm will probably require a decent one though again what are you needs? Are you sure you need to rev that high to meet them?

[GTR1993]

I think you need to have a look at this thread

http://www.performanceforums.com/forums/sh....php?t=67218679

He had a gt60 and its just too big, he now has a precision turbo good for 2000 hp and is a shit load lighter then the garrett turbo.

Check it out.

Edited December 27, 2007 by GTR1993

[VB-]

no way i'd go for any of those turbos, you'll make some nice power but only for about 500rpm right before redline, that motor is just too small IMO

bigger turbo doesnt mean you'll g faster, look at something like a GT45 at the most, and you'll have power through the rev range, not just on top of it. with too big of a turbo, you just wont spend any time making power. put it on the quater and you'd struggle to run a 13

[TwinTurboM3]

Nice.

The Reason I Sounded Dubious At first is there are a lot of school students who claim to own all these rediculous cars.

I see the car is LHD so your in the US im Guessing.

Pistons I Personally would go Cosworth Custom Same with Con-Rods as by the looks of it There is no budget on this thing you are building.

Make sure you line bore the Billet mains with them torqued into place because of the difference in materials used (cast iron block - Steel Mains)

As For the Turbo I cant comment Because GT55 and GT60 Mean Nothing with out details like Trim, Comp and Exh A/R Etc Etc.

Yes left hand drive. I am from the sphincter of the universe, not from US.

Budget is the last restriction, in these projects, if one tends to follow the economy root, results are disaster.

May I ask what you mean by LINE BORE BILLET? is this torque honing with the plate?

I am not a professional, do it as a hobby, and got a dynamics twin retarder dyno. www.da-motorsport.com is my page, not professional, but as a hobby.

GT55 with 91 mm comp wheel and 1.0 A/R spools at 6000-6300 rpm on a 3.4L supra with lots of head modification, with full race exhaust manifold.

So, on a 3.9L, full spool should be around 5300 - 5500 rpm. Assuming all variables are well matched and done.

[zebra]

What i mean is you need to bolt the mains caps down and hone them so they match. they also have different thermal expansion rates between the two different types of material (iron and steel) So from memory it needs to be done at normal operating temps of the block but dont quote me.

Speak to a high end engine builder who has expirence with billet steel mains on a cast iron block (you may have to ring the USA to get your answers)

A question though......why would you want power coming on at 6000rpm? that would just piss me off

nothing, nothing, nothing, nothing, wheel spin, rev limiter, change gear, then do it all over again

[TwinTurboM3]

Hi Mr twin turbo M3, if the twin GT30R is really yours the I am pretty sure we've communicated albeit under slightly different names.

There is only one trim comp/turbine setting for the GT55 and GT60 turbos out there - they have an awesomely wide map and aren't likely to build boost quick enough to surge on a 3.9litre anyway. It'd make sense to go one of the smallest turbine a/rs on a BMW.

You mention rev range etc - what boost level/power level are you actually after? GT5591 is a HUGE turbo, I'd not even consider a GT60 and barely think about a GT55. The GT60 you showed, and the only other GT60 I've seen used were both on 26Bs which would provide a shiteload more exhaust gas than a 3.9l BMW though I guess you have to consider compressor efficiency, spinning a 3.9 to near 9000rpm will probably require a decent one though again what are you needs? Are you sure you need to rev that high to meet them?

Power is as much as the block will handle:) Stroke of 3.9L is 91 mm so we have safe piston speeds @ 9000 rpm. As a result, i will be safely revving 9ooo rpm. There will be more safety precautions such as sleeving the block and use of L19 studs.

Power should be as much as possible, fuel will be C16 all time as we wont use this car. I do not mention power, as our Dyno Dynamics reads lower less than US dynos. But the base power will be 300- 320 whp, in naturally aspirated trim. Goal is high compression ratio, serious port and polish.

Having a strong base power and boosting 30 to 45 psi will end up with nice figures, Assuming all go well and engine stays one piece.

One important point is: different cams and different A/Rs will be tested and the best combination will be found. It is a hobby so i will take it easy and go step by step.

[TwinTurboM3]

What i mean is you need to bolt the mains caps down and hone them so they match. they also have different thermal expansion rates between the two different types of material (iron and steel) So from memory it needs to be done at normal operating temps of the block but dont quote me.

Speak to a high end engine builder who has expirence with billet steel mains on a cast iron block (you may have to ring the USA to get your answers)

A question though......why would you want power coming on at 6000rpm? that would just piss me off

nothing, nothing, nothing, nothing, wheel spin, rev limiter, change gear, then do it all over again

Zebra.

Thank you for your interest.

I own a M3, which you saw above, equipped with twin GT3076s. This M3, may have full boost @ 5000 rpm. And rev 9000 rpm. (stock limiter is set @ 8ooo rpm) .

On the M3 i have a drivable and acceptable power band.

Other than the M3, i also have a 2,8L BMW inline with twin GT2871s. This 2.8L is making full boost at 4700 rpm and revving 8ooo rpm. Still acceptable.

When i was building the M3 3.2L with twin GT3076s and my 2,8L with twin GT2871, i was reading this forum and also gtr.co.uk and was trying to find out how Gt3037s of HKS responded on RB26 and RB30s.

Thanks to members of these 2 forums, I have great feedback.

SO far i did test the 2.8L twin Gt2871 on the road, was spooling @ 4700 rpm, A/Rs 0,64 on the hot side.

When the M3 twin GT3076 will be done i will post dyno dynamics graphs here as well.

Why did i tell you this story?

M3 twin GT3076 and 2.8L twin Gt2871 are drivable on road. 100 octane pump fuel of Shell is used. So still daily.

On the other side, the new project with 3.9L and GT??? will be used just for:

RACING BIG BOYS. There are some 900 whp supras in the sphincter of the universe, one of them made 830 whp on my dynamics. And there are some 7.0L corvettes with 350-500 hp nitroussss.

So with the 3.9L, just pure racing goal, C16 used all time, exhaust discharged straight to the pavement, no silencer, no interior, JUSTA BOMB to test with big boys on highway rolls.

For highway rolls between 100 km/h to 280 km/h this latest project will respond and compete with big boys.

What do you say?

mert

[R34GTFOUR]

i say that would be fun haha

goodluck with it

[Lithium]

What do you say?

Errr, any tires you could use on a street aren't likely to hold the power a maxed out GT5591R or bigger would make :S I'd probably stick to putting something like that on a tube framed drag car with huge slicks.

Here is a GTR running 4 full slicks black tracking down the dragstrip - running a lowly GT4508R: